| 摘要 |
PROBLEM TO BE SOLVED: To provide a light intensity detecting unit capable of reducing the change in the quantity of light received by a light reception portion, to provide an optical system, to provide an exposure apparatus, and to provide a method of manufacturing a device.SOLUTION: The light intensity detecting unit 25 includes a second beam splitter 26 and a third beam splitter 27 that can reflect at least part of incident exposure light EL, and a second photoelectric sensor 29 and a third photoelectric sensor 30 that receive reflected light beams from the second beam splitter 26 and third beam splitter 27. On a side of the light intensity detecting unit 25 which is closer to a light source than the second beam splitter 26, a 1/2-wavelength plate 32 is disposed which rotates a linear polarized component of the exposure light EL with respect to the second beam splitter 26 so as to make small the change in quantity of light received by the second photoelectric sensor 29 and third photoelectric sensor 30 when the angle of incidence of the exposure light EL on the second beam splitter 26 changes. |
